Ive had 2 and they are awesome esc's.Currently using on in my 33' mono on 6s...They are the best bang for your buck boating esc out right now! Just get one and dont look back..
Heres one in my CyberStorm on 6s..

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I dont see any sizes of the flex shaft or collet..Your gonna want to use .187 flex..As for the strut you have, that would work good with a flooded stuffing tube but I would probably opt for a stinger instead..